Forced draft device for steam boilers



Feb. 29, 1944. P. H. ROUTLEDGE FORCED DRAFT DEVTCE FOR $TEAM BOILERS Filed March 27, 1941 IN VENTOR k PERCY 1/0/2010 K0 0 rt 50 q 5 ATTORN E Y.

Patented Feb. 29, 1944 warren STATEg FOR CED DRAFT DEVICE FOR STEA'M BOILERS Percy Harold Routledge, Mission, British Columbia, Canada Application March 27, 1941, Serial No. 385,562

('01. 2s0 1oo) 3 Claims.

' My invention relates to improvements in forced draft devices for steam boilers which are particularly adapted for use in locomotives. The bjects of the invention are to utilize the exhaust steam from reciprocatory engines to provide a substantially constant and steady flow of gases from the fire box of the engine boiler through the smoke stack, also to provide for a general re-- duction of the back pressure on the engine, and to provide means for adjusting the operative parts to obtain eflicient service at all stages of engine load from starting up to normal running conditions.

The invention consists essentially of a Venturi ejector structure including a cone for confining and directing the exhaust steam through the Venturi throat and an inner cone concentric therewith, as will be more fully described in the following specification and shown in the accompanying drawing, in which:

Fig. 1 is a plan view of the smoke box of a locomotive showing the ejector as taken on the line l--l of Figure 2.

Fig. 2 is a front elevational view of the invention.

Fig. 3 is a transverse sectional view of the ejector cones and adjusting means therefor.

Figs. 4 and 5 are fractionated sectional views showing different positions of adjustment of the inner cone.

In the drawing like characters of reference indicate corresponding parts in each figure.

The numeral I indicates generally a locomotive frame upon which a saddle 2 is mounted to support the front end or smoke box 3 of the locomotive boiler. Engine castings 4 are secured to the frame I and extend upwards to connect directly to the lower peripheral wall of the smoke box 3. Each engine casting includes a working cylinder 5 and a piston valve cylinder '5 and exhaust passages I are formed in the castings as indicated in dotted line in Figure 2 which communicate with opposite ends of the piston valve cylinders. The several exhaust passages I lead respectively to flanges III, II, l2 and I3, the flanges H! and H communicate respectively with the rear and forward ends of the piston valve cylinder 6 of the left engine and the flanges i2 and 13 communicate respectively with the forward. and rear end of the piston valve cylinder 6 of the right engine of the locomotive. To each of the flanges H), H, l2 and I3, pipes l4, l5, H5 and ll are connected, which communicate with the lower peripheral wall l8 of a cone l 9 tangentially.

The upper end of the cone l9 terminates in a Venturi throat or jet 22 having a slightfiare 23 at its tip. I The cone I9 'is enclosed with a bottom Wall 24 having a bearing 25 in which a vertical shaft 26 is journalled. The shaft is threaded at its upper end as at 2? and'engages a cross member 28 of an inner cone 29 which is telescopically mounted in a collar 33 carried from the bottom wall 24. The inner cone 29 is pro- Vided with guide pins 3! which project through the bottom wall to prevent said cone from turning with the shaft 28. The shaft 26 is rotated by mitre gears 33 from a horizontal shaft 34 which is'operated from the cab of the locomotive by any suitable means. The inner cone 29 is fitted at its apex with a ball 36 which is adapted, when the cone is in its lowermost position as shown in Figure 4, to define a very narrow annular passage through the throat 22. V

Mounted in the wall 38 of the smoke box 3 is a smoke stack 39 formed of two opposed frustoconical portions 40 and M with throat or point of greatest constriction at their intersection as at 42. The length of the lower portion 40 and the disposition of the throat 42 with respect to the jet 22 of the cone I9 is designed to provide for the proper filling of the stack 39 with smoke entering the stack from the interspace 44 between the top of the cone I9 and the base of the stack.

The operation of the device is as follows: When about to start the locomotive the inner cone 29 is lowered until the horizontal axis of the ball 33 is in a plane coincident to the top of the cone I9 and the inner cone wall is at its greatest distance from the inner surfaces of the cone l9, thus producing a conical steam passage 45 therebetween of maximum width. Each engine cylinder exhausts its steam into the conical steam passage 45 and flows therearound spirally towards the jet. The resulting bursts of exhaust steam following each other at close intervals, set up a steam flow which becomes substantially continuous before it passes through the jet and also sets up a fiow of progressively increasing velocity due to the decrease of diameter of the annular passage 45 towards the top of the cones. As the steam reaches the jet 21. its velocity is high and due to the narrowing down of the passage between the jet 22 and the ball 33 its flow is still further increased to a point where there is substantially no interval between successive ex hausts, consequently the steam flowing at high and constant speed serves to provide a consistently high vacuum in the smoke box and at the base of the stack. This high speed steam flow traveling spirally upwards becomes constant at the point of discharge from the cone and due to momentum lessens the pressure on each of the exhaust pipes I4, l5, l6 and I? at the time when their respective exhaust valves are closed, hence the initial back pressure against the pistons of the engine is materially reduced and greater power is obtained from said engines for a given quantity of steam. As the inertia of the load is being overcome and momentum is increased to enable the cut off to take place earlier a lesser volume of steam will be exhausted per stroke, though the number of exhausts will be increased per unit of time, the volume of steam exhausted however being less than when starting it is desirable to raise the cone accordingly so as to reduce the width of the passage 45 while projecting the ball 36 beyond the jet 22 as shown in Figure 5, when the ball will serve to spread the steam as it passes through the jet to fill the stack 39 and maintain the same negative pressure within the smoke box 3.

What I claim as my invention is:

1. An ejector comprising a circular chamber having a peripheral wall and a top opening and a tubular member concentric with and spaced above the top opening, exhaust pip connections communicating with the chamber through said peripheral wall, a vertically movable member be-- tween the exhaust pipe connections and the top opening defining a passage leading to said opening, said member having an enlargement adapted to reduce the effective cross sectional area of the passage through the top opening when said memher is in its lowermost position and to project through the opening to increase the effective cross sectional area of the opening when the member is in raised position.

2. An ejector comprising a chamber having a base and a frustoconical wall terminating in a top opening and a tubular member concentric with and spaced above the top opening, a verticall movable cone Within the chamber having an enlargement supported above its apex, exhaust pipe connections communicating with the base of the chamber, said enlargement being so disposed above the cone as to reduce the effective cross area of the top opening when the cone is in its lowermost position and to increase the eifective cross sectional area of the top opening as the cone is raised Within the chamber.

3. An ejector comprising a chamber having a base and a frustocom'cal wall terminating in a top opening and a tubular member concentric with and spaced above the top opening, a vertically movable cone within the chamber having a spherical enlargement supported above its apex, exhaust pipe connections communicating with the base of the chamber, said enlargement being so disposed with respect to the top opening as to provide a narrow annular passage through said opening when the cone is in its lowermost position and to increase the Width of the annular passage as the cone and said enlargement are raised.

PERCY HAROLD ROUTLEDGE. 

